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Profile Retvari Zoltan
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Message 38586 - Posted: 20 Oct 2014 | 13:07:23 UTC

We had a power failure late at night on last Thursday. This happened before, but not the way like this time.
We have LED bulbs which are more sensitive to the power surges and flicker much more frequently than incandescent and fluorescent lighting. They did flicker this time just before the electricity went out completely. The power came back for a half second, but then it went out permanently. I saw that the lighting in our staircase is on (we live in a 4 storied apartment house), so I thought the source of this power failure is near. I've checked all of our fuses, but all of them were ok. I was puzzled for a minute, but then I've heard that the other resident from a floor below came out to check their fuses in the staircase. It turned out that half of the apartments lost electricity in the building. I went to the ground floor to search for the blown fuse. I've met a guy from the ground floor, he heard a bang before the power went out in their apartment, which is a pretty bad sign. We found 2 fuse-boxes, both have a large emergency power switch (3 phased), but their handle was missing (to prevent some stupid pranks...). However the spindle of the bigger switch felt lukewarm, so I knew that something burned inside, and we couldn't fix this on our own. At this moment I've decided to call an electrician... It was after midnight, so it took a while to find the one who answered our call.
So the electrician found the burnt fuse panel, and the two blown and burnt fuses, and a wire whose insulation was burned / melt down completely.

The burnt / blown fuses, the fuse panel, and the naked wire:

The wire (and its termination) is made of aluminium, which is a pretty bad conductor and has a pretty high contact resistance, and used to corrode the contact when connected with other metals like brass. Probably that led to this meltdown. (The electrician said those screws wasn't fastened well enough, they could became loose over time from the vibration caused by the traffic, especially the tramway near to our building). Aluminium was used as a replacement for copper wires during and after WWII (when our block was built).
I know that this failure wasn't caused only by my constant power consumption (10~12A @ 230V), but it certainly had the biggest part in it. The lesson is those who use that much electric power should not skip the maintenance of the wires in the building for 70 years...

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Message 38595 - Posted: 20 Oct 2014 | 23:08:18 UTC

Hi Zoltan,

Quite a story. I hope you don't have any damage to your hardware, I know you have quite a nice farm of rigs.
All the best.
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Greetings from TJ

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Message 38601 - Posted: 21 Oct 2014 | 11:34:59 UTC

We have the same thing here in the US, aluminum and copper wires mixed in the same building. The need for maintenance is never passed on from owner to owner and eventually someone gets burned, I HOPE your guy went thru what he could to ensure a reduced possibility of any future occurrences. Here in the US some people even went so far as to have all the aluminum wires removed, but that can be a VERY expensive process, especially for you with 4 stories!! In the US though the process of mixing, in new construction, is now banned by the Electrical Code, some places follow the Code and some don't. But MOST Electricians are aware of the problem and are hopefully informing the owners.

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Message 38617 - Posted: 21 Oct 2014 | 14:40:14 UTC

There might have been a power surge that contributed to the failure. They can be due to lightning strikes, or even switching of equipment with high inductive loads (e.g., motors). I had a whole-house surge suppressor installed recently, though whether it does any good won't be known for a long time. Also, I use series surge suppressors (Zero Surge) for each PC.

Profile Retvari Zoltan
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Message 38621 - Posted: 21 Oct 2014 | 18:19:17 UTC - in response to Message 38595.

Hi Zoltan,

Quite a story. I hope you don't have any damage to your hardware, I know you have quite a nice farm of rigs.
All the best.

Thanks TJ!

I was afraid that, but luckily nothing damaged, except my RAC as some workunits failed and one was stucked and running for 44 hours before I've noticed.

TJ
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Message 38625 - Posted: 21 Oct 2014 | 22:06:24 UTC - in response to Message 38621.

Hi Zoltan,

Quite a story. I hope you don't have any damage to your hardware, I know you have quite a nice farm of rigs.
All the best.

Thanks TJ!

I was afraid that, but luckily nothing damaged, except my RAC as some workunits failed and one was stucked and running for 44 hours before I've noticed.

I am happy for you Zoltan, no damage.
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Greetings from TJ

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Message 38630 - Posted: 22 Oct 2014 | 10:59:06 UTC

Great to hear you had no damage to your computer equipment.

It's interesting to see that bit of copper wire twisted around one of the fuse (contacts?). I wonder why that was there? A poor fix for a bad contact/connection?

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Message 38631 - Posted: 22 Oct 2014 | 11:25:38 UTC - in response to Message 38617.

There might have been a power surge that contributed to the failure. They can be due to lightning strikes, or even switching of equipment with high inductive loads (e.g., motors). I had a whole-house surge suppressor installed recently, though whether it does any good won't be known for a long time. Also, I use series surge suppressors (Zero Surge) for each PC.


I too had a whole house one put in and he told me there is no longer any need for one for every pc? Are you being extra careful or did your guy say something different? Mine was about 150 US Dollars for the part, I live in a 4 bedroom 3 story, including the basement, home. My guy did at the same time he put in 3 20 amp circuits for my pc's. No more blowing of the circuit breakers is a GOOD thing!

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Message 38635 - Posted: 22 Oct 2014 | 13:58:26 UTC - in response to Message 38631.
Last modified: 22 Oct 2014 | 14:12:37 UTC

I too had a whole house one put in and he told me there is no longer any need for one for every pc? Are you being extra careful or did your guy say something different? Mine was about 150 US Dollars for the part, I live in a 4 bedroom 3 story, including the basement, home. My guy did at the same time he put in 3 20 amp circuits for my pc's. No more blowing of the circuit breakers is a GOOD thing!

I actually had the Zero Surge protectors in place first, and added the whole-house one later when I replaced the circuit breakers. It may be over-kill, but you don't get a second chance with surges. And the whole-house one will protect the lights. It is said that the premature failures that you sometimes get with the compact fluorescent light bulbs are due to power spikes, so maybe that will do some good.

I also have uninterruptible power supplies (UPS) on each PC (plugged into each Zero Surge), which provide some surge protection, though that is not their main function. They are there because I use a ramdisk on some of the PCs for storing the BOINC data folder. That causes all the writes to go to main memory, protecting the SSD from the high write rate of CEP2, but I then have to controllably shut down each PC with the UPS in case of a power failure, so that the contents of the ramdisk can be written into the SSD before it is lost. Otherwise, I would not really need the UPS.

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Message 38636 - Posted: 22 Oct 2014 | 14:22:24 UTC - in response to Message 38630.

Great to hear you had no damage to your computer equipment.

It's interesting to see that bit of copper wire twisted around one of the fuse (contacts?). I wonder why that was there? A poor fix for a bad contact/connection?

We was wondering about it too. There could be two reasons for that:
1. The fuse was short circuited for some reason (bigger then 50A load for a short time)
2. Dodge the electronic meter by bypassing it.

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Message 38638 - Posted: 22 Oct 2014 | 18:09:53 UTC

Aluminum wiring is bad news and worse news if it's mixed with copper. On top of the safety hazards (50-60 times more likely to start a fire than with full copper wiring) many insurance companies now refuse to insure houses with aluminum wiring. There are ways to make aluminum safer by using proper connectors but the best thing to do is to avoid it if possible.

One of many articles on the subject:

http://homeguides.sfgate.com/problems-aluminum-copper-wire-electricity-86313.html

Coincidently I once owned a home with aluminum wiring and even though it was only a few years old I found outlets and switches that would get hot with very little load. Whenever I found one I tore it apart and installed proper connectors and paste to cut down oxidation but would never knowingly buy a house with any aluminum wiring again.

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Message boards : Number crunching : Dangers of crunching

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